The proposed study is designed to determine whether particulates alter the allergic response to allergens, and to identify inflammatory markers of particulate allergic responses, as well as phenotypic markers of susceptibility to particulate altered allergic responses. Allergen-induced responses in the nasal cavity will be utilized as model of allergic inflammation. A single-blind randomized cross-over design will be used to test the allergic responses in 60 subjects over the five-year period of the study. Allergic responses will be assessed using cellular and biochemical markers of inflammation following recovery by nasal lavage. In addition, in situ hybridization will be used to assess cytokine mRNA expression; nasal symptoms and measures of nasal airflow and patency (acoustic rhinometry) will also be used as biomarkers for allergic responses. The investigator proposes that the techniques of nasal lavage, acoustic rhinometry and in situ hybridization may prove useful in the development of markers of particle altered allergic responses and can ultimately be applied to epidemiological studies, as well as the identification of susceptible individuals to particle altered allergic responses. It is proposed that identification of these phenotypic characteristics can eventually be utilized for the development of therapeutic interventions targeted towards susceptible individuals. The investigators characterizes this proposed project as a launching point for research on the roles played by ambient pollutants in allergic disease by developing validated markers that can be applied readily in epidemiological studies investigating particulate-allergen interactions.